Modulation of Cav3.1 T-type Ca2+ channels by the ran binding protein RanBPM

In order to Study the currently unknown cellular signaling pathways of Ca(v)3.1 T-type channels Ca2+ (Ca(v)3.1 channels), we performed a yeast two-hybrid screening using intracellular domains of Ca(v)3.1 alpha 1 subunit as bait. After screening the human brain cDNA library, several proteins, including RanBPM, were identified as interacting with Ca(v)3.1 channels. RanBPM was found to bind to the cytoplasmic intracellular loop between transmembrane domains I and II of Ca(v)3.1 channels. Using whole-cell patch-clamp techniques, we found that Ca(v)3.1 currents were increased by the expression of RanBPM in HEK293/Ca(v)3.1 cells, We next examined whether RanBPM affected the biophysical properties and plasma membrane expression of Ca(v)3.1 channels. Furthermore, we showed that the PKC activator inhibited Ca(v)3.1 currents, an effect that was abolished by the expression of RanBPM. These results suggest that RanBPM could be a key regulator of Ca(v)3.1 channel-mediated signaling pathways. (C) 2008 Published by Elsevier Inc.